what should I do when my daughter beat her self when she get angry
Just ignore it...eventually, when she realizes she's not getting a reaction from u--she will stop. Like Mandyloo said, she really can't be hurting herself. If she starts to beat her head against things, of course this must be stopped and she needs to realize she can't hurt herself. Pick her up and put her directly into her playpen where she can't hurt herself. She'll realize again that she still isn't getting the type of attention she wants and she will eventually stop.
How old is she and how bad does she beat herself? If it's just small hits - she is not harming herself and she knows her pain tolerance and how hard she can hit herself without it hurting. I'm guessing she is really young - she's just throwing a temper tantrum. Also, if she sees that it get's a reaction out of you when you hit yourself - she learns that you wil pay attention or give in when she does that.